(1) Field of the Invention
The present invention relates to a gas injection device and a solar cell manufacturing method using the same.
(2) Description of the Related Art
Solar cells convert sunlight energy into electrical energy. Solar cells are important clean energy or next-generation energy that replaces fossil energy which causes a greenhouse effect due to discharge of carbon dioxide (CO2) and replaces nuclear energy which contaminates an earth environment such as air pollution due to radioactive waste.
The solar cells basically generate electricity using two kinds of semiconductors such as a P-type semiconductor and an N-type semiconductor. When the solar cells are used as a light absorbing layer, they are classified into various kinds depending on materials used therein.
The solar cell has a general structure in which a front transparent conductive layer, a P-N layer, and a rear reflecting electrode layer are deposited on a substrate in sequence. When sunlight is incident to the solar cell of the structure, electrons are collected on the N layer and holes are collected on the P layer, to thereby generate electric current.
A compound solar cell (copper-indium-gallium-selenide, “CIGS”) has high efficiency to convert sunlight into electricity without using silicon unlike known silicon based solar cells. The CIGS may be formed by depositing copper (Cu), indium (In), gallium (Ga) and selenium (Se) compounds on an electrode formed on flexible substrates such as stainless, aluminum, etc., as well as a glass substrate.
In a conventional solar cell, a CIGS (Cu, In, Ga, Se) compound layer may be formed by injecting hydrogen selenide (H2Se) on a mixed layer of copper (Cu), indium (In), and gallium (Ga) after the mixed layer of copper (Cu), indium (In), and gallium (Ga) is formed.
In a conventional method of forming the solar cell, the hydrogen selenide (H2Se) may be injected through a gas pipeline in a gas injection device. As area of the solar cell becomes larger, the injecting area of the hydrogen selenide (H2Se) becomes larger, and the length of the gas pipeline also becomes longer. As the length of the gas pipeline becomes longer, the number of nozzles attached to the gas pipeline is also increased, such that difference of discharge rate of nozzles disposed between an inlet and an outlet of the gas pipeline is generated because pressure is decreased due to channel friction loss in the gas pipeline and discharge rate through the nozzles. Accordingly, since the injecting amount of the hydrogen selenide (H2Se) is not uniform in the conventional method of forming the solar cell, the CIGS (Cu, In, Ga, Se) compound layer is not uniform.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore contains information that does not form any part of the prior art.